I had started to add mkv support, but didn’t get too far as I was more interested in getting dvr processing working. Also, didn’t find a python based editor for mkv metadata; currently using Mutagen for mp4 tagging.
@c.megalodon, the DVR post bug appears when there is more than one file in the .grab directory when DVRd shows are recorded. When Plex goes to move files to their final location, all but one disappears. A more detailed discussion is in this thread .
Also, what were the ffmpeg errors when going to mp4?
